// 笔迹开始
function uploadScaleStart(e) {
    console.log('笔迹开始',this.ctx);
    if (e.type != 'touchstart') return false;
    let ctx = this.data.ctx;
    ctx.setFillStyle(this.data.lineColor); // 初始线条设置颜色

    ctx.setGlobalAlpha(this.data.transparent); // 设置半透明

    let currentPoint = {
        x: e.touches[0].x,
        y: e.touches[0].y
    };
    let currentLine = this.data.currentLine;
    currentLine.unshift({
        time: new Date().getTime(),
        dis: 0,
        x: currentPoint.x,
        y: currentPoint.y
    });
    this.setData({
        currentPoint // currentLine
    });

    if (this.data.firstTouch) {
        this.setData({
            cutArea: {
                top: currentPoint.y,
                right: currentPoint.x,
                bottom: currentPoint.y,
                left: currentPoint.x
            },
            firstTouch: false
        });
    }

    this.pointToLine(currentLine);
} // 笔迹移动

function uploadScaleMove(e) {
    if (e.type != 'touchmove') return false;

    if (e.cancelable) {
        // 判断默认行为是否已经被禁用
        if (!e.defaultPrevented) {
            e.preventDefault();
        }
    }

    let point = {
        x: e.touches[0].x,
        y: e.touches[0].y
    }; //测试裁剪

    if (point.y < this.data.cutArea.top) {
        this.data.cutArea.top = point.y;
    }

    if (point.y < 0) this.data.cutArea.top = 0;

    if (point.x > this.data.cutArea.right) {
        this.data.cutArea.right = point.x;
    }

    if (this.data.canvasWidth - point.x <= 0) {
        this.data.cutArea.right = this.data.canvasWidth;
    }

    if (point.y > this.data.cutArea.bottom) {
        this.data.cutArea.bottom = point.y;
    }

    if (this.data.canvasHeight - point.y <= 0) {
        this.data.cutArea.bottom = this.data.canvasHeight;
    }

    if (point.x < this.data.cutArea.left) {
        this.data.cutArea.left = point.x;
    }

    if (point.x < 0) this.data.cutArea.left = 0;
    this.setData({
        lastPoint: this.data.currentPoint,
        currentPoint: point
    });
    let currentLine = this.data.currentLine;
    currentLine.unshift({
        time: new Date().getTime(),
        dis: this.distance(this.data.currentPoint, this.data.lastPoint),
        x: point.x,
        y: point.y
    }); // this.setData({
    //   currentLine
    // })

    this.pointToLine(currentLine);
} // 笔迹结束

function uploadScaleEnd(e) {
    if (e.type != 'touchend') return 0;
    let point = {
        x: e.changedTouches[0].x,
        y: e.changedTouches[0].y
    };
    this.setData({
        lastPoint: this.data.currentPoint,
        currentPoint: point
    });
    let currentLine = this.data.currentLine;
    currentLine.unshift({
        time: new Date().getTime(),
        dis: this.distance(this.data.currentPoint, this.data.lastPoint),
        x: point.x,
        y: point.y
    }); // this.setData({
    //   currentLine
    // })

    if (currentLine.length > 2) {
        var info = (currentLine[0].time - currentLine[currentLine.length - 1].time) / currentLine.length; //$("#info").text(info.toFixed(2));
    } //一笔结束，保存笔迹的坐标点，清空，当前笔迹
    //增加判断是否在手写区域；

    this.pointToLine(currentLine);
    var currentChirography = {
        lineSize: this.data.lineSize,
        lineColor: this.data.lineColor
    };
    var chirography = this.data.chirography;
    chirography.unshift(currentChirography);
    this.setData({
        chirography
    });
    var linePrack = this.data.linePrack;
    linePrack.unshift(this.data.currentLine);
    this.setData({
        linePrack,
        currentLine: []
    });
}

function retDraw() {
    this.data.ctx.clearRect(0, 0, 700, 730);
    this.data.ctx.draw();
} //画两点之间的线条；参数为:line，会绘制最近的开始的两个点；

function pointToLine(line) {
    this.calcBethelLine(line);
    return;
} //计算插值的方式；

function calcBethelLine(line) {
    if (line.length <= 1) {
        line[0].r = this.data.radius;
        return;
    }

    let x0,
        x1,
        x2,
        y0,
        y1,
        y2,
        r0,
        r1,
        r2,
        len,
        lastRadius,
        dis = 0,
        time = 0,
        curveValue = 0.5;

    if (line.length <= 2) {
        x0 = line[1].x;
        y0 = line[1].y;
        x2 = line[1].x + (line[0].x - line[1].x) * curveValue;
        y2 = line[1].y + (line[0].y - line[1].y) * curveValue; //x2 = line[1].x;
        //y2 = line[1].y;

        x1 = x0 + (x2 - x0) * curveValue;
        y1 = y0 + (y2 - y0) * curveValue;
    } else {
        x0 = line[2].x + (line[1].x - line[2].x) * curveValue;
        y0 = line[2].y + (line[1].y - line[2].y) * curveValue;
        x1 = line[1].x;
        y1 = line[1].y;
        x2 = x1 + (line[0].x - x1) * curveValue;
        y2 = y1 + (line[0].y - y1) * curveValue;
    } //从计算公式看，三个点分别是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)这个是控制点，控制点不会落在曲线上；实际上，这个点还会手写获取的实际点，却落在曲线上

    len = this.distance(
        {
            x: x2,
            y: y2
        },
        {
            x: x0,
            y: y0
        }
    );
    lastRadius = this.data.radius;

    for (let n = 0; n < line.length - 1; n++) {
        dis += line[n].dis;
        time += line[n].time - line[n + 1].time;
        if (dis > this.data.smoothness) break;
    }

    this.setData({
        radius: Math.min((time / len) * this.data.pressure + this.data.lineMin, this.data.lineMax) * this.data.lineSize
    });
    line[0].r = this.data.radius; //计算笔迹半径；

    if (line.length <= 2) {
        r0 = (lastRadius + this.data.radius) / 2;
        r1 = r0;
        r2 = r1; //return;
    } else {
        r0 = (line[2].r + line[1].r) / 2;
        r1 = line[1].r;
        r2 = (line[1].r + line[0].r) / 2;
    }

    let n = 5;
    let point = [];

    for (let i = 0; i < n; i++) {
        let t = i / (n - 1);
        let x = (1 - t) * (1 - t) * x0 + 2 * t * (1 - t) * x1 + t * t * x2;
        let y = (1 - t) * (1 - t) * y0 + 2 * t * (1 - t) * y1 + t * t * y2;
        let r = lastRadius + ((this.data.radius - lastRadius) / n) * i;
        point.push({
            x: x,
            y: y,
            r: r
        });

        if (point.length == 3) {
            let a = this.ctaCalc(point[0].x, point[0].y, point[0].r, point[1].x, point[1].y, point[1].r, point[2].x, point[2].y, point[2].r);
            a[0].color = this.data.lineColor; // let bethelPoint = this.data.bethelPoint;
            // console.log(a)
            // console.log(this.data.bethelPoint)
            // bethelPoint = bethelPoint.push(a);

            this.bethelDraw(a, 1);
            point = [
                {
                    x: x,
                    y: y,
                    r: r
                }
            ];
        }
    }

    this.setData({
        currentLine: line
    });
} //求两点之间距离

function distance(a, b) {
    let x = b.x - a.x;
    let y = b.y - a.y;
    return Math.sqrt(x * x + y * y);
}

function ctaCalc(x0, y0, r0, x1, y1, r1, x2, y2, r2) {
    let a = [],
        vx01,
        vy01,
        norm,
        n_x0,
        n_y0,
        vx21,
        vy21,
        n_x2,
        n_y2;
    vx01 = x1 - x0;
    vy01 = y1 - y0;
    norm = Math.sqrt(vx01 * vx01 + vy01 * vy01 + 0.0001) * 2;
    vx01 = (vx01 / norm) * r0;
    vy01 = (vy01 / norm) * r0;
    n_x0 = vy01;
    n_y0 = -vx01;
    vx21 = x1 - x2;
    vy21 = y1 - y2;
    norm = Math.sqrt(vx21 * vx21 + vy21 * vy21 + 0.0001) * 2;
    vx21 = (vx21 / norm) * r2;
    vy21 = (vy21 / norm) * r2;
    n_x2 = -vy21;
    n_y2 = vx21;
    a.push({
        mx: x0 + n_x0,
        my: y0 + n_y0,
        color: '#1A1A1A'
    });
    a.push({
        c1x: x1 + n_x0,
        c1y: y1 + n_y0,
        c2x: x1 + n_x2,
        c2y: y1 + n_y2,
        ex: x2 + n_x2,
        ey: y2 + n_y2
    });
    a.push({
        c1x: x2 + n_x2 - vx21,
        c1y: y2 + n_y2 - vy21,
        c2x: x2 - n_x2 - vx21,
        c2y: y2 - n_y2 - vy21,
        ex: x2 - n_x2,
        ey: y2 - n_y2
    });
    a.push({
        c1x: x1 - n_x2,
        c1y: y1 - n_y2,
        c2x: x1 - n_x0,
        c2y: y1 - n_y0,
        ex: x0 - n_x0,
        ey: y0 - n_y0
    });
    a.push({
        c1x: x0 - n_x0 - vx01,
        c1y: y0 - n_y0 - vy01,
        c2x: x0 + n_x0 - vx01,
        c2y: y0 + n_y0 - vy01,
        ex: x0 + n_x0,
        ey: y0 + n_y0
    });
    a[0].mx = a[0].mx.toFixed(1);
    a[0].mx = parseFloat(a[0].mx);
    a[0].my = a[0].my.toFixed(1);
    a[0].my = parseFloat(a[0].my);

    for (let i = 1; i < a.length; i++) {
        a[i].c1x = a[i].c1x.toFixed(1);
        a[i].c1x = parseFloat(a[i].c1x);
        a[i].c1y = a[i].c1y.toFixed(1);
        a[i].c1y = parseFloat(a[i].c1y);
        a[i].c2x = a[i].c2x.toFixed(1);
        a[i].c2x = parseFloat(a[i].c2x);
        a[i].c2y = a[i].c2y.toFixed(1);
        a[i].c2y = parseFloat(a[i].c2y);
        a[i].ex = a[i].ex.toFixed(1);
        a[i].ex = parseFloat(a[i].ex);
        a[i].ey = a[i].ey.toFixed(1);
        a[i].ey = parseFloat(a[i].ey);
    }

    return a;
}

function bethelDraw(point, is_fill, color) {
    let ctx = this.data.ctx;
    ctx.beginPath();
    ctx.moveTo(point[0].mx, point[0].my);

    if (undefined != color) {
        ctx.setFillStyle(color);
        ctx.setStrokeStyle(color);
    } else {
        ctx.setFillStyle(point[0].color);
        ctx.setStrokeStyle(point[0].color);
    }

    for (let i = 1; i < point.length; i++) {
        ctx.bezierCurveTo(point[i].c1x, point[i].c1y, point[i].c2x, point[i].c2y, point[i].ex, point[i].ey);
    }

    ctx.stroke();

    if (undefined != is_fill) {
        ctx.fill(); //填充图形 ( 后绘制的图形会覆盖前面的图形, 绘制时注意先后顺序 )
    }

    ctx.draw(true);
}

function selectColorEvent(event) {
    console.log(event);
    var color = event.currentTarget.dataset.colorValue;
    var colorSelected = event.currentTarget.dataset.color;
    this.setData({
        selectColor: colorSelected,
        lineColor: color
    });
} //设置canvas背景色  不设置  导出的canvas的背景为透明
//@params：字符串  color

function setCanvasBg(color) {
    console.log(999);
    /* 将canvas背景设置为 白底，不设置  导出的canvas的背景为透明 */
    //rect() 参数说明  矩形路径左上角的横坐标，左上角的纵坐标, 矩形路径的宽度, 矩形路径的高度
    //这里是 canvasHeight - 4 是因为下边盖住边框了，所以手动减了写

    this.data.ctx.rect(0, 0, this.data.canvasWidth, this.data.canvasHeight - 4); // ctx.setFillStyle('red')

    this.data.ctx.setFillStyle(color);
    this.data.ctx.fill(); //设置填充

    this.data.ctx.draw(); //开画
}

module.exports = {
    uploadScaleStart,
    uploadScaleMove,
    uploadScaleEnd,
    retDraw,
    pointToLine,
    calcBethelLine,
    distance,
    ctaCalc,
    bethelDraw,
    selectColorEvent,
    setCanvasBg
};
